This file is an exploratory analysis of the effect of climate-induced shifts in angler catch-per-trip of Gulf of Maine cod and haddock. Results are based on 100 iterations of the recreation demand model. The RDM is calibrated to 2020 fishery conditions.
Mean monthly bottom temps by decade, red line indicates decadal average. Bars represent mean monthly temp +/- 1.96*standard dev.
Projected differences in average monthly sea bottom temperatures relative to 2020. Bars represent lower and upper bounds of the projected average monthly temperatures. Red lines indicate differences between the decadal and 2020 annual average.
Index “_i” indicates per choice occasion variable
variable mean sd
draw 50.5 29.0115
estimated_trips 312755.1 0.9653
n_choice_occasions 483934 2193.714
tot_cod_catch 588077.5 1903.489
tot_keep_cod 5044.494 53.3831
tot_rel_cod 583033 1897.925
tot_hadd_catch 1918895 4220.46
tot_keep_hadd 1004515 2038.446
tot_rel_hadd 914379.9 2380.872
cod_keep_i 0.0104 1e-04
hadd_keep_i 2.0758 0.0091
cod_keep_trip 0.0161 2e-04
hadd_keep_trip 3.2118 0.0065
cod_catch_i 1.2152 0.0067
hadd_catch_i 3.9653 0.018
cod_catch_trip 1.8803 0.0061
hadd_catch_trip 6.1355 0.0135
After calibrating the simulation model to 2020 fishery conditions, I re-ran the model under two closure scenarios: (a) bag limits for both cod and haddock set to zero, and (b) bag limits for cod only set to zero.
\(~\)
CV per choice occasion
mean sd
62.88 0.44
Aggregate CV
mean sd
30461985 157733.2
Number of trips under closure
mean sd
260020.2 549.17
Number of trips under baseline fishery
mean sd
312754.9 1.01
Percent reduction in trips from baseline fishery
mean sd
-16.86 0.18
CV per choice occasion
mean sd
0.89 0.18
Aggregate CV
mean sd
429052 85388.3
Number of trips under closure
mean sd
312081.8 153.72
Number of trips under baseline fishery
mean sd
312754.9 1.01
Percent reduction in trips from baseline fishery
mean sd
-0.22 0.05
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Each tab contains projected fishery outcomes based on input data from alternative copula models. #### Changes catch outcomes and temperatures relative to 2020
Cod and haddock keep per choice occasion:
Cod and haddock catch per choice occasion:
Total CV and number of trips:
Correlation in catch and keep of cod and haddock per choice occasion (kendall’s tau-b):
Cod and haddock keep per choice occasion:
Cod and haddock catch per choice occasion:
Total CV and number of trips:
Correlation in catch and keep of cod and haddock per choice occasion (kendall’s tau-b):
Cod and haddock keep per choice occasion:
Cod and haddock catch per choice occasion:
Total CV and number of trips:
Correlation in catch and keep of cod and haddock per choice occasion (kendall’s tau-b):
Cod and haddock keep per choice occasion:
Cod and haddock catch per choice occasion:
Total CV and number of trips:
Correlation in catch and keep of cod and haddock per choice occasion (kendall’s tau-b):
Cod and haddock keep per choice occasion:
Cod and haddock catch per choice occasion:
Total CV and number of trips:
Correlation in catch and keep of cod and haddock per choice occasion (kendall’s tau-b):
The following OLS regression uses as data the 10 sets of results above (5 copulas, each with independent and correlated catch).
OLS results of total monthly CV
For reference, here are the number of directed trips by mode and period (1st and 2nd half of month) in 2020.
MRIP point estimates of directed trips in 2020 by bi-monthly period
Each tab below contains projected fishery outcomes at the monthly level based on input data from alternative copula models.
Number of trips by month:
CV per choice occasion by month:
Cod keep per choice occasion by month:
Haddock keep per choice occasion by month:
Cod catch per choice occasion by month:
Haddock catch per choice occasion by month:
Correlation in catch of cod and haddock per choice occasion (kendall’s tau-b):
Number of trips by month:
CV per choice occasion by month:
Cod keep per choice occasion by month:
Haddock keep per choice occasion by month:
Cod catch per choice occasion by month:
Haddock catch per choice occasion by month:
Correlation in catch of cod and haddock per choice occasion (kendall’s tau-b):
Number of trips by month:
CV per choice occasion by month:
Cod keep per choice occasion by month:
Haddock keep per choice occasion by month:
Cod catch per choice occasion by month:
Haddock catch per choice occasion by month:
Correlation in catch of cod and haddock per choice occasion (kendall’s tau-b):
Number of trips by month:
CV per choice occasion by month:
Cod keep per choice occasion by month:
Haddock keep per choice occasion by month:
Cod catch per choice occasion by month:
Haddock catch per choice occasion by month:
Correlation in catch of cod and haddock per choice occasion (kendall’s tau-b):
Number of trips by month:
CV per choice occasion by month:
Cod keep per choice occasion by month:
Haddock keep per choice occasion by month:
Cod catch per choice occasion by month:
Haddock catch per choice occasion by month:
Correlation in catch of cod and haddock per choice occasion (kendall’s tau-b):
In these simulations, I vary the cod open season across different months of the year.
The baseline (2020) open season for cod was Sep. 15-30 for private boat and September 7-October 8 for for-hire. Because the model time-step is bi-monthly (two periods per month: 1st half, 2nd half), I set the baseline private boat open season to the 2nd half of September and the baseline for-hire season to the 1st and 2nd half of September. Haddock was open all months in the baseline except March and the first half of April, when there was no directed trips.
I specified alternative cod open seasons by month for May, June, July, August, and October. To do this, I open the 2nd half of the month for private boat mode, and I open the 1st and 2nd half of the month for the for-hire mode.
In these simulations I use independent and correlated catch-per-trip data from the clayton copula model.
CV results below show the difference in total CV between cod open season of September and cod open season occurring an alternative month.
Cod and haddock keep per choice occasion:
Cod and haddock catch per choice occasion:
CV per choice occasion and number of trips:
Correlation in catch and keep of cod and haddock per choice occasion (kendall’s tau-b):
In these simulations, I vary the cod open season across different months of the year. The results here come from #2a above but are presented at the monthly level.
Number of trips by month:
CV per choice occasion by month:
Cod keep per choice occasion by month:
Haddock keep per choice occasion by month:
Cod catch per choice occasion by month:
Haddock catch per choice occasion by month:
Correlation in catch of cod and haddock per choice occasion (kendall’s tau-b):
Number of trips by month:
CV per choice occasion by month:
Cod keep per choice occasion by month:
Haddock keep per choice occasion by month:
Cod catch per choice occasion by month:
Haddock catch per choice occasion by month:
Correlation in catch of cod and haddock per choice occasion (kendall’s tau-b):
Number of trips by month:
CV per choice occasion by month:
Cod keep per choice occasion by month:
Haddock keep per choice occasion by month:
Cod catch per choice occasion by month:
Haddock catch per choice occasion by month:
Correlation in catch of cod and haddock per choice occasion (kendall’s tau-b):
Number of trips by month:
CV per choice occasion by month:
Cod keep per choice occasion by month:
Haddock keep per choice occasion by month:
Cod catch per choice occasion by month:
Haddock catch per choice occasion by month:
Correlation in catch of cod and haddock per choice occasion (kendall’s tau-b):
Number of trips by month:
CV per choice occasion by month:
Cod keep per choice occasion by month:
Haddock keep per choice occasion by month:
Cod catch per choice occasion by month:
Haddock catch per choice occasion by month:
Correlation in catch of cod and haddock per choice occasion (kendall’s tau-b):
Number of trips by month:
CV per choice occasion by month:
Cod keep per choice occasion by month:
Haddock keep per choice occasion by month:
Cod catch per choice occasion by month:
Haddock catch per choice occasion by month:
Correlation in catch of cod and haddock per choice occasion (kendall’s tau-b):